Navy Yard shootings

The flags surrounding the Washington Monument fly at half-staff as ordered by President Barack Obama following the deadly shooting Monday at the Washington Navy Yard, Tuesday morning, Sept. 17, 2013, in Washington. (AP Photo/J. Scott Applewhite)

Essential personnel are allowed into a closed Washington Navy Yard in Washington, on Tuesday, Sept. 17, 2013, the day after a gunman launched an attack inside the Washington Navy Yard on Monday, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital. (AP Photo/Jacquelyn Martin)

Three women embrace near Nationals Park where family members waited to greet loved ones that were at the Washington Navy Yard, Monday Sept. 16, 2013, in Washington. At least one gunman launched an attack inside the Washington Navy Yard, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital, authorities said. (AP Photo/Alex Brandon)

A U.S. Park Police helicopter removes a man in a basket from the Washington Navy Yard Monday, Sept. 16, 2013. Earlier in the day, the U.S. Navy said it was searching for an active shooter at the Naval Sea Systems Command headquarters, where about 3,000 people work. The exact number of people killed and the conditions of those wounded was not immediately known. (AP Photo/Jacquelyn Martin)

Police work the scene on M Street, SE in Washington near the Washington Navy Yard on Monday, Sept. 16, 2013. (AP Photo/Jacquelyn Martin)

A U.S. Capitol Police officer keeps watch on the East Plaza of the Capitol as the investigation continues at the nearby Washington Navy Yard where at least one gunman went on a shooting rampage, Monday, Sept. 16, 2013, in Washington. (AP Photo/J. Scott Applewhite)

A U.S. Park Police helicopter continues a search pattern above the scene of a shooting at the Washington Navy Yard on Monday, Sept. 16, 2013 in Washington. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning, and officials said several people were killed and more were wounded, including a law enforcement officer. (AP Photo/ Evan Vucci)

Law enforcement personnel are seen outside the gate into the Washington Navy Yard in Washington, Monday, Sept. 16, 2013. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning, and officials said several people were killed and more were wounded, including a law enforcement officer. (AP Photo/Susan Walsh)

Law enforcement personnel are seen through the gate into the Washington Navy Yard in Washington, Monday, Sept. 16, 2013. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning, and officials said several people were killed and more were wounded, including a law enforcement officer. (AP Photo/Susan Walsh)

U.S. Capitol Police personnel keep watch on the East Plaza of the Capitol as the investigation continues to the shooting at the nearby Washington Navy Yard Monday, Sept. 16, 2013, in Washington. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning. (AP Photo/J. Scott Applewhite)

The main street near the Washington Navy Yard is crowded with official vehicles following a shooting at the Washington Navy Yard in Washington, Monday, Sept. 16, 2013. At least one gunman opened fire inside a building at the Washington Navy Yard on Monday morning (AP Photo/Susan Walsh)

District of Columbia Police Chief Cathy Lanier briefs reporters on the shooting at the Washington Navy Yard in Washington, Monday, Sept. 16, 2013, where at least one gunman opened fire inside a building at the Washington Navy Yard. (AP Photo/Susan Walsh)

A reporter knocks on the door of the last known address of Aaron Alexis Monday, Sept. 16, 2013, in Fort Worth, Texas. Police have identified Alexis as the gunman in Monday's shooting rampage at at the Washington Navy Yard in Washington. Mayor Vincent Gray said at a news conference Monday afternoon that Alexis was among the dead. (AP Photo/LM Otero)

These images released by the FBI show photos of Aaron Alexis, who police believe was a gunman at the Washington Navy Yard shooting in Washington, Monday morning, Sept. 16, 2013, and who was killed after he fired on a police officer. At least one gunman launched an attack inside the Washington Navy Yard, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital, authorities said. The photo at left is from 2011. (AP Photo/FBI)

A police officer gives instructions to people coming out of the main gate of the Washington Navy Yard facility who were trapped inside during a lock down when at least one gunman launched an attack inside a building at the Navy Yard, Monday, Sept. 16, 2013. (AP Photo/Manuel Balce Ceneta)

Secretary of the Navy Ray Mabus speaks during a news conference at Washington Hospital Center, in Washington, on Monday, Sept. 16, 2013, after visiting the people injured in the shooting at the Washington Navy Yard. At least one gunman launched an attack inside the Washington Navy Yard, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital, authorities said. (AP Photo/Jose Luis Magana)

People hold their hands to their heads as they are escorted out of the building where a deadly shooting rampage occurred at the Washington Navy Yard in Washington, Monday, Sept. 16, 2013. One shooter was killed, but police said they were looking for two other possible gunmen wearing military-style uniforms. (AP Photo/Jacquelyn Martin)

A U.S. Capitol Police officer patrols the steps at the Capitol as the investigation continues at the nearby Washington Navy Yard where at least one gunman opened fire, Monday, Sept. 16, 2013, in Washington. (AP Photo/J. Scott Applewhite)

Police responding to the shooting at the Washington Navy Yard, deploy on the rooftop of a Navy Yard building in Washington, Monday, Sept. 16, 2013. (AP Photo/Manuel Balce Ceneta)

Nii Oti-Ankrah, left, kisses his wife Sally Appiah-Ankrah as he holds their son Eilam Ankrah after she was evacuated from building 197 at the Washington Navy Yard, Monday Sept. 16, 2013 in Washington. At least one gunman launched an attack inside the Washington Navy Yard, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital, authorities said. (AP Photo/Alex Brandon)

Restaurant owner Oui Suthamtewakul, right, and Michael Ritrovato speak about working with Aaron Alexis , who was once employed by Suthamtewakul, Monday, Sept. 16, 2013, in Fort Worth, Texas. Police have identified Alexis as the gunman in Monday's shooting rampage at at the Washington Navy Yard in Washington. Mayor Vincent Gray said at a news conference Monday afternoon that Alexis was among the dead. (AP Photo/LM Otero)

A small group holds a candle light vigil on Freedom Plaza to remember the victims of the shooting at the Washington Navy Yard, Monday, Sept. 16, 2013, in Washington. (AP Photo/J. Scott Applewhite)

A small group holds a candle light vigil on Freedom Plaza to remember the victims of the shooting at the Washington Navy Yard, Monday, Sept. 16, 2013, in Washington. (AP Photo/J. Scott Applewhite)

Staff of the Naval Sea Systems Command headquarters exchange a salute while being greeted by family and friends as they are bused from the Washington Navy Yard to Nationals Park, in Washington, Monday, Sept. 16, 2013. At least one gunman launched an attack inside the Washington Navy Yard, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital, authorities said. (AP Photo/Jacquelyn Martin)

Family and friends wait to greet staff of the Naval Sea Systems Command headquarters as they are bused from the Washington Navy Yard to Nationals Park, in Washington, Monday, Sept. 16, 2013. At least one gunman launched an attack inside the Washington Navy Yard, spraying gunfire on office workers in the cafeteria and in the hallways at the heavily secured military installation in the heart of the nation's capital, authorities said. (AP Photo/Jacquelyn Martin)